Ecologists still don’t believe in fairies. But it may take magic to resolve a long-running debate over what causes the oddly regular spots of bare soil called fairy circles. A new approach now suggests combining the two main hypotheses.

Fairy circles, each among about six close neighbors, sprinkle arid grasslands in southern Africa and Australia “like a polka dot dress,” says ecologist Corina Tarnita of Princeton University. Two persistent ideas fuel debate over what’s making the arrays: stalemate warfare between underground termite colonies (SN Online: 3/28/13) or bigger plants monopolizing water (SN: 4/16/16, p. 8). “What if the reason that this debate is so long-lasting and it’s so hard to dismiss the other hypothesis is that both are right to a certain extent?” Tarnita asks.
Termites, by themselves, can in theory cause the mysterious arrangements, Tarnita, Princeton ecologist Robert Pringle and colleagues conclude from a new mathematical model they developed. They then linked their insect model with one showing plant competition causing fairy circles. The combined approach unexpectedly predicted a previously undescribed regular “clumping” pattern among the plants between fairy circles, the team reports January 18 in Nature.

In aerial pictures of fairy circles, the plants look like an even sea of vegetation between bare spots. To see if the plant patterns were real, the researchers visited the Namib Desert in southern Africa. Local park personnel “were constantly confused,” Tarnita says, because visitors usually study the bare patches. The vegetation clumped as predicted, in roughly hexagonal arrays as the circles themselves do. That confirmation suggests the combined model was working, the researchers say.

Hexagonal arrangements show up repeatedly in nature as creatures crowd together — for instance, as bees arrange cells in honeycombs, Pringle says. In southern Africa, termite colonies might create circular bare spots when insect nibbling prevents plant growth above the nest. Colonies too evenly matched to destroy each other persist as neighboring disks of barren soil, eventually packing into roughly hexagonal arrays.
But plants by themselves can make similar bare spots in harsh conditions, Tarnita explains. When a pioneer plant springs from dry, hot ground, for instance, opportunists follow, taking advantage of such benefits as the scrap of shade a pioneer casts. As these secondary plants grow bigger and suck up more of the limited water, they can create dead zones where nothing sprouts. Over time, these zones form hexagonal patterns, too.
Termites plus plants are probably producing the effect in the Namib Desert, Tarnita says. But the results might not apply to other fairy circle hot spots, such as Australia, she cautions. The main message of the new paper is that “different processes can lead to the exact same pattern,” she says.

Two proponents of the long-standing theories aren’t convinced the termite and plant models should be combined. Termite advocate Norbert Jürgens of the University of Hamburg welcomes the part of the new model that social insects alone “clearly” can cause fairy circles. But he’s not sure the plant clumping between circles indicates anything important. “Yes, of course there are always small-scale patterns among neighboring plants that are caused by feedback mechanisms,” he says. “However, these do not cause fairy circles.”

Nor does the new paper convert an ecologist advocating plant competition as the driver of fairy circle formation. Just showing that termites by themselves could create arrays with six neighbors isn’t enough, says Stephan Getzin of the Helmholtz Centre for Environmental Research GmbH-UFZ in Leipzig, Germany. “The degree of ordering or regularity that is shown by their insect model is not as strong as the ordering of [real-world] fairy circles,” he objects.

What’s needed now to resolve the debate isn’t necessarily fairy dust. Tarnita says she’s hoping for outdoor experiments.

Salmonella bacteria don’t want your body to starve on their account. The microbes’ motives, though, are (probably) purely poop-related.

The body sometimes sacrifices appetite to fight off infection: Less energy for the host also means less energy for the pathogen. Understanding how bacteria cope with this tactic can inform treatments.

When it reaches the gut, Salmonella enterica bacteria can trigger this type of anorexic response in their host, making it a good model for how microbes deal with less food. Researchers at the Salk Institute in California investigated salmonella fallout in mice. In lab tests, they found that the bacteria aren’t as virulent when a mouse isn’t eating, and they use the vagus nerve, a superhighway connecting gut to brain, to encourage eating. The bacteria make a protein called SIrP that appears to block signals that dampen appetite.

Keeping a host well fed plays out in the pathogen’s favor, the researchers write January 26 in Cell. That food has to go somewhere, and excreted waste gives salmonella place to live and an opportunity to spread.

Sleep is at the top of the list of conversation starters among parents with young children. With our recent cross-country move west, my family added a twist on sleep deprivation: jet-lagged children. To get some clarity on this new horror, I called developmental social scientist A.J. Schwichtenberg of Purdue University in West Lafayette, Ind.

Two main processes control sleep, Schwichtenberg explained. The first is the constant buildup of sleepiness, a pressure to sleep called homeostatic drive. Like adults, children reach a certain point and need to crash. “The longer they’re awake, the more likely it is they’ll want to go to sleep,” Schwichtenberg says. But unlike adults, children reach their limits sooner. That’s why most kids need to nap.

In the background of this sleepiness buildup is a roughly 24-hour daily rhythm. Called a circadian cycle, this rhythm is regulated by cues such as light, activity and even meals. When sleepiness coincides with a dark room, the result is usually blissful rest.

In the days after our recent move to the West Coast, however, this beautiful alignment went awry. Although the room was dark and quiet at 4 a.m., the two youngest people in our family were most definitely not sleepy.

After a few minutes of listening to my daughters whisper-shout about the funny hotel alarm clock, it finally sunk in: These kids were wide awake and ready to go. After all, their body clocks were still on the East Coast, where it was a reasonable 7 a.m. So like any conscientious parent, I threw an iPhone at them with unlimited Peppa Pig. That bought us a half hour. After that, my husband and I chugged hotel coffee and accepted our zombie fate.

In retrospect, Peppa might not have been the best choice. Schwichtenberg recommends keeping those obscenely early mornings dark and quiet. “You don’t want the world to be a superexciting place,” she says. Expose your child to the local time zone cues as much as possible. That means darkness when it’s time to sleep, lots of sunlight when it’s time to be awake, and meals at the right times.

The strongest of these reset cues is light, says Lisa Medalie, a behavioral sleep medicine specialist at University of Chicago Medicine. Sunlight in the morning tells the brain to be awake at the new time, she says. And at the end of the day, blue light, the kind emitted by electronic screens, should be avoided. Blue light dampens levels of the sleep-inducing hormone melatonin. To avoid this, screens ought to be turned off one hour before bedtime, she says.
Your newborn might escape jet lag entirely. Babies aren’t born with a solid circadian rhythm. Scientists think it takes about three months for babies to learn, with the help of lights and sounds, when to sleep and when to be awake (a skill my 2-year-old still struggles with). That means that if you are bravely traveling with a brand-spanking-new baby, jet lag might not be a big concern. “They sleep so much anyway, Schwichtenberg says. “There’s not a distinction between day and night.”

For quick trips of three days or less with older babies and kids, it might be best to just keep the whole crew on the same schedule as back home. In that time frame, it’s going to be difficult to shift cycles back and forth. The rule of thumb is that a person shifts about an hour per day.

If you’re going to be gone for longer than three days, you may want to begin shifting your child’s clock before you leave. An hour in either direction is a good place to start, Schwichtenberg says. We could have prepared our girls by having them stay up later than usual before our westward journey. And for the travel day itself, Schwichtenberg recommends traveling during the day. “Work your flight to arrive in the afternoon or evening,” so that your child will be tired on arrival, around the time for bed.

If you’ve traveled east and find yourself with a wired kid at 10 p.m., you might be tempted to turn to a drowse-inducing antihistamine such as Benadryl. But for some people, antihistamines can cause the opposite — disastrous — side effect of hyperactivity. Other drugs such as melatonin can be hard to dose correctly for young infants, Schwichtenberg says.

When trying to get older children to sleep, try to keep some semblance of normalcy. If you do a bedtime routine at home, use the same one while traveling. The biological plausibility of warm milk as a sleep aid isn’t settled, but it’s worth a shot. (Never underestimate the power of placebo.) Whatever you do, don’t despair. Your child will eventually adjust to her new time zone and you’ll get a full night’s sleep, at least until the next tooth erupts.

A tsunami’s immense wall of water may not be stoppable. But there may be a way to take the ferocious force of nature down a few notches, using a pair of counterwaves.

If released at the right moment, a type of sound wave known as an acoustic-gravity wave could subdue a tsunami, applied mathematician Usama Kadri of Cardiff University in Wales reports January 23 in Heliyon. These acoustic-gravity waves, which reach deep below the ocean’s surface, can stretch tens or hundreds of kilometers and easily travel long distances at high speeds.

In Kadri’s plan, two acoustic-gravity waves would be launched through the water at the earthquake-triggered ocean surge. The waves would be tuned to exchange energy with the tsunami as they speed past, spreading the tsunami out by redistributing its energy and thereby decreasing its maximum height.

The tsunami sapper is still theoretical — scientists don’t yet have a way to create the high-energy waves needed. But Kadri suggests his approach could have shrunk the amplitude of the devastating 2004 Indian Ocean tsunami by almost 30 percent. Such a reduction translates to a five-meter decrease in the height the water reached above sea level, enough to potentially save lives and property.